Abstract

Dielectric behavior on artificial lattices has been investigated along with quantum mechanical simulation (first principles calculation). From the oxide artificial lattice approach, strain manipulation was performed to obtain a wide range of lattice deformation in the consisting and layers, which leads to two important consequences. First, we obtained enhanced dielectric constant and extremely large nonlinearity in the artificial lattices with very short stacking periods. Second, it is found that there exists a maximum dielectric constant in each lattice and lattice at a certain degree of lattice deformation. The first principles study successfully explains the dielectric behavior of strained and lattices, the existence of the maximum dielectric constant. The first principles study on artificial lattices with very short stacking periods also reveals that the artificial lattice undergoes phase transition between the tetragonal and monoclinic phases with a misfit lattice strain and exhibits an anomalous dielectric behavior at the phase boundary. Optical phonon behavior of the artificial lattice resembles that of strained lattice and optical phonon softening primarily derives the anomaly of the dielectric tensor at the phase boundary. The lattice deformation is a primary influencing factor to phonon and dielectric behaviors rather than interface layer effect in artificial lattice with very short stacking periods.

Received 28 February 2005Accepted 26 June 2006Published online 19 September 2006

Acknowledgments:

This work is supported by the Korea Science and Engineering Foundation (KOSEF) through National Research Laboratory (NRL) Program and CAPST, and the Ministry of Trade, Industry, and Energy through System IC2010 Program. The authors thank K. M. Rabe at Rutgers University and J. B. Neaton at University of California, Berkeley for valuable help in first principles calculation.